Drug-induced nightmares

OBJECTIVE: TO compile and assess the English-language literature on drug-in duced nightmares, excluding nightmares secondary to drug withdrawal or drug -associated night terrors. DATA SOURCES: Published articles, letters, case reports, and abstracts in E nglish were identified by MEDLINE (1966-May 1998) searches using the search term nightmares, chemically induced. Additional articles were obtained fro m bibliographies of retrieved articles. DATA EXTRACTION: All case reports of drug-induced nightmares were evaluated using the Naranjo algorithm for causality. Clinical studies of drugs that reported nightmares as an adverse effect were assessed for frequency of occ urrence. DATA SYNTHESIS: Nightmares, defined as nocturnal episodes of intense anxiet y and fear associated with a vivid, emotionally charged dream experience, a re generally classified as a parasomnia. Possible pharmacologic mechanisms for drug-induced nightmares, such as REM suppression and dopamine receptor stimulation, are reviewed. However, the vast majority of therapeutic agents implicated in causing nightmares have no obvious pharmacologic mechanism. CONCLUSIONS: Assessing causality with an event such as a nightmare is diffi cult because of the high incidence of nightmares in the healthy population. Using qualitative, quantitative, and possible pharmacologic mechanism crit eria, it appears that sedative/hypnotics, beta-blockers, and amphetamines a re the therapeutic modalities most frequently associated with nightmares. T hese drug classes have a plausible pharmacologic mechanism to explain this effect. Dopamine agonists also have evidence of causality, with dopamine re ceptor stimulation as a possible pharmacologic mechanism.